Hello there, @peggyg.

I can see that you've been experiencing this issue since 2018. I'd suggest performing the troubleshooting method. This is done to identify what is causing your settings to change by itself, resulting to uncheck the box for Automatically remember account or transaction information.

You can start with updating the QuickBooks Desktop, to get the latest data into the program. Here's how:

1. Go to the Help menu.
2. Click Update QuickBooks Desktop.
3. Go to the Update Now tab.
4. Put a check on the box beside Reset Update.
5. Select Get Updates.

Once done, restart the QuickBooks program. Then, check the box that has the Automatically remember account or transaction information and click Save. It should look like this:

Then, try to test it with a few transactions. Restart the program and try to create a new test transaction to see if it works. If you're still unable to see the auto-fill details, I'd recommend using the Verify and Rebuild tools. This is done to fix any data issues in the company file.

Please note you'll need to create a backup file before using these tools. You can check out this article to learn more about the steps: Verify and Rebuild Data in QuickBooks Desktop. 

You can always tag my name in the comment section if you have other questions. I'm here to answer them. Take care.